/*
 *    This program is free software; you can redistribute it and/or modify
 *    it under the terms of the GNU General Public License as published by
 *    the Free Software Foundation; either version 2 of the License, or
 *    (at your option) any later version.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU General Public License for more details.
 *
 *    You should have received a copy of the GNU General Public License
 *    along with this program; if not, write to the Free Software
 *    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 *    Attribute.java
 *    Copyright (C) 1999 Eibe Frank
 *
 */

package weka.core;

import java.io.Serializable;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Properties;
import java.io.StreamTokenizer;
import java.io.StringReader;
import java.io.IOException;

/** 
 * Class for handling an attribute. Once an attribute has been created,
 * it can't be changed. <p>
 *
 * The following attribute types are supported:
 * <ul>
 *    <li> numeric: <br/>
 *         This type of attribute represents a floating-point number.
 *    </li>
 *    <li> nominal: <br/>
 *         This type of attribute represents a fixed set of nominal values.
 *    </li>
 *    <li> string: <br/>
 *         This type of attribute represents a dynamically expanding set of
 *         nominal values. Usually used in text classification.
 *    </li>
 *    <li> date: <br/>
 *         This type of attribute represents a date, internally represented as 
 *         floating-point number storing the milliseconds since January 1, 
 *         1970, 00:00:00 GMT. The string representation of the date must be
 *         <a href="http://www.iso.org/iso/en/prods-services/popstds/datesandtime.html" target="_blank">
 *         ISO-8601</a> compliant, the default is <code>yyyy-MM-dd'T'HH:mm:ss</code>.
 *    </li>
 * </ul>
 * 
 * Typical usage (code from the main() method of this class): <p>
 *
 * <code>
 * ... <br>
 *
 * // Create numeric attributes "length" and "weight" <br>
 * Attribute length = new Attribute("length"); <br>
 * Attribute weight = new Attribute("weight"); <br><br>
 * 
 * // Create vector to hold nominal values "first", "second", "third" <br>
 * FastVector my_nominal_values = new FastVector(3); <br>
 * my_nominal_values.addElement("first"); <br>
 * my_nominal_values.addElement("second"); <br>
 * my_nominal_values.addElement("third"); <br><br>
 *
 * // Create nominal attribute "position" <br>
 * Attribute position = new Attribute("position", my_nominal_values);<br>
 *
 * ... <br>
 * </code><p>
 *
 * @author Eibe Frank (eibe@cs.waikato.ac.nz)
 * @version $Revision: 1.32.2.3 $
 */
public class Attribute implements Copyable, Serializable {

	/** Constant set for numeric attributes. */
	public static final int NUMERIC = 0;

	/** Constant set for nominal attributes. */
	public static final int NOMINAL = 1;

	/** Constant set for attributes with string values. */
	public static final int STRING = 2;

	/** Constant set for attributes with date values. */
	public static final int DATE = 3;

	/** Constant set for symbolic attributes. */
	public static final int ORDERING_SYMBOLIC = 0;

	/** Constant set for ordered attributes. */
	public static final int ORDERING_ORDERED  = 1;

	/** Constant set for modulo-ordered attributes. */
	public static final int ORDERING_MODULO   = 2;

	/** The keyword used to denote the start of an arff attribute declaration */
	static String ARFF_ATTRIBUTE = "@attribute";

	/** A keyword used to denote a numeric attribute */
	static String ARFF_ATTRIBUTE_INTEGER = "integer";

	/** A keyword used to denote a numeric attribute */
	static String ARFF_ATTRIBUTE_REAL = "real";

	/** A keyword used to denote a numeric attribute */
	static String ARFF_ATTRIBUTE_NUMERIC = "numeric";

	/** The keyword used to denote a string attribute */
	static String ARFF_ATTRIBUTE_STRING = "string";

	/** The keyword used to denote a date attribute */
	static String ARFF_ATTRIBUTE_DATE = "date";

	/** Strings longer than this will be stored compressed. */
	private static final int STRING_COMPRESS_THRESHOLD = 200;

	/** The attribute's name. */
	private /*@ spec_public non_null @*/ String m_Name;

	/** The attribute's type. */
	private /*@ spec_public @*/ int m_Type;
	/*@ invariant m_Type == NUMERIC || 
                m_Type == DATE || 
                m_Type == STRING || 
                m_Type == NOMINAL;
	 */

	/** The attribute's values (if nominal or string). */
	private /*@ spec_public @*/ FastVector m_Values;

	/** Mapping of values to indices (if nominal or string). */
	private Hashtable m_Hashtable;

	/** Date format specification for date attributes */
	private SimpleDateFormat m_DateFormat;

	/** The attribute's index. */
	private /*@ spec_public @*/ int m_Index;

	/** The attribute's metadata. */
	private ProtectedProperties m_Metadata;

	/** The attribute's ordering. */
	private int m_Ordering;

	/** Whether the attribute is regular. */
	private boolean m_IsRegular;

	/** Whether the attribute is averagable. */
	private boolean m_IsAveragable;

	/** Whether the attribute has a zeropoint. */
	private boolean m_HasZeropoint;

	/** The attribute's weight. */
	private double m_Weight;

	/** The attribute's lower numeric bound. */
	private double m_LowerBound;

	/** Whether the lower bound is open. */
	private boolean m_LowerBoundIsOpen;

	/** The attribute's upper numeric bound. */
	private double m_UpperBound;

	/** Whether the upper bound is open */
	private boolean m_UpperBoundIsOpen;

	/**
	 * Constructor for a numeric attribute.
	 *
	 * @param attributeName the name for the attribute
	 */
	//@ requires attributeName != null;
	//@ ensures  m_Name == attributeName;
	public Attribute(String attributeName) {

		this(attributeName, new ProtectedProperties(new Properties()));
	}

	/**
	 * Constructor for a numeric attribute, where metadata is supplied.
	 *
	 * @param attributeName the name for the attribute
	 * @param metadata the attribute's properties
	 */
	//@ requires attributeName != null;
	//@ requires metadata != null;
	//@ ensures  m_Name == attributeName;
	public Attribute(String attributeName, ProtectedProperties metadata) {

		m_Name = attributeName;
		m_Index = -1;
		m_Values = null;
		m_Hashtable = null;
		m_Type = NUMERIC;
		setMetadata(metadata);
	}

	/**
	 * Constructor for a date attribute.
	 *
	 * @param attributeName the name for the attribute
	 * @param dateFormat a string suitable for use with
	 * SimpleDateFormatter for parsing dates.
	 */
	//@ requires attributeName != null;
	//@ requires dateFormat != null;
	//@ ensures  m_Name == attributeName;
	public Attribute(String attributeName, String dateFormat) {

		this(attributeName, dateFormat,
				new ProtectedProperties(new Properties()));
	}

	/**
	 * Constructor for a date attribute, where metadata is supplied.
	 *
	 * @param attributeName the name for the attribute
	 * @param dateFormat a string suitable for use with
	 * SimpleDateFormatter for parsing dates.
	 * @param metadata the attribute's properties
	 */
	//@ requires attributeName != null;
	//@ requires dateFormat != null;
	//@ requires metadata != null;
	//@ ensures  m_Name == attributeName;
	public Attribute(String attributeName, String dateFormat,
			ProtectedProperties metadata) {

		m_Name = attributeName;
		m_Index = -1;
		m_Values = null;
		m_Hashtable = null;
		m_Type = DATE;
		if (dateFormat != null) {
			m_DateFormat = new SimpleDateFormat(dateFormat);
		} else {
			m_DateFormat = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss");
		}
		m_DateFormat.setLenient(false);
		setMetadata(metadata);
	}

	/**
	 * Constructor for nominal attributes and string attributes.
	 * If a null vector of attribute values is passed to the method,
	 * the attribute is assumed to be a string.
	 *
	 * @param attributeName the name for the attribute
	 * @param attributeValues a vector of strings denoting the 
	 * attribute values. Null if the attribute is a string attribute.
	 */
	//@ requires attributeName != null;
	//@ ensures  m_Name == attributeName;
	public Attribute(String attributeName, 
			FastVector attributeValues) {

		this(attributeName, attributeValues,
				new ProtectedProperties(new Properties()));
	}

	/**
	 * Constructor for nominal attributes and string attributes, where
	 * metadata is supplied. If a null vector of attribute values is passed
	 * to the method, the attribute is assumed to be a string.
	 *
	 * @param attributeName the name for the attribute
	 * @param attributeValues a vector of strings denoting the 
	 * attribute values. Null if the attribute is a string attribute.
	 * @param metadata the attribute's properties
	 */
	//@ requires attributeName != null;
	//@ requires metadata != null;
	/*@ ensures  m_Name == attributeName;
      ensures  m_Index == -1;
      ensures  attributeValues == null && m_Type == STRING
            || attributeValues != null && m_Type == NOMINAL 
                  && m_Values.size() == attributeValues.size();
      signals (IllegalArgumentException ex) 
                 (* if duplicate strings in attributeValues *);
	 */
	public Attribute(String attributeName, 
			FastVector attributeValues,
			ProtectedProperties metadata) {

		m_Name = attributeName;
		m_Index = -1;
		if (attributeValues == null) {
			m_Values = new FastVector();
			m_Hashtable = new Hashtable();
			m_Type = STRING;
		} else {
			m_Values = new FastVector(attributeValues.size());
			m_Hashtable = new Hashtable(attributeValues.size());
			for (int i = 0; i < attributeValues.size(); i++) {
				Object store = attributeValues.elementAt(i);
				if (((String)store).length() > STRING_COMPRESS_THRESHOLD) {
					try {
						store = new SerializedObject(attributeValues.elementAt(i), true);
					} catch (Exception ex) {
						System.err.println("Couldn't compress nominal attribute value -"
								+ " storing uncompressed.");
					}
				}
				if (m_Hashtable.containsKey(store)) {
					throw new IllegalArgumentException("A nominal attribute (" +
							attributeName + ") cannot"
							+ " have duplicate labels (" + store + ").");
				}
				m_Values.addElement(store);
				m_Hashtable.put(store, new Integer(i));
			}
			m_Type = NOMINAL;
		}
		setMetadata(metadata);
	}

	/**
	 * Produces a shallow copy of this attribute.
	 *
	 * @return a copy of this attribute with the same index
	 */
	//@ also ensures \result instanceof Attribute;
	public /*@ pure non_null @*/ Object copy() {

		Attribute copy = new Attribute(m_Name);

		copy.m_Index = m_Index;
		copy.m_Type = m_Type;
		copy.m_Values = m_Values;
		copy.m_Hashtable = m_Hashtable;
		copy.m_DateFormat = m_DateFormat;
		copy.setMetadata(m_Metadata);

		return copy;
	}

	/**
	 * Returns an enumeration of all the attribute's values if
	 * the attribute is nominal or a string, null otherwise. 
	 *
	 * @return enumeration of all the attribute's values
	 */
	public final /*@ pure @*/ Enumeration enumerateValues() {

		if (isNominal() || isString()) {
			final Enumeration ee = m_Values.elements();
			return new Enumeration () {
				public boolean hasMoreElements() {
					return ee.hasMoreElements();
				}
				public Object nextElement() {
					Object oo = ee.nextElement();
					if (oo instanceof SerializedObject) {
						return ((SerializedObject)oo).getObject();
					} else {
						return oo;
					}
				}
			};
		}
		return null;
	}

	/**
	 * Tests if given attribute is equal to this attribute.
	 *
	 * @param other the Object to be compared to this attribute
	 * @return true if the given attribute is equal to this attribute
	 */
	public final /*@ pure @*/ boolean equals(Object other) {

		if ((other == null) || !(other.getClass().equals(this.getClass()))) {
			return false;
		}
		Attribute att = (Attribute) other;
		if (!m_Name.equals(att.m_Name)) {
			return false;
		}
		if (isNominal() && att.isNominal()) {
			if (m_Values.size() != att.m_Values.size()) {
				return false;
			}
			for (int i = 0; i < m_Values.size(); i++) {
				if (!m_Values.elementAt(i).equals(att.m_Values.elementAt(i))) {
					return false;
				}
			}
			return true;
		} else {
			return (type() == att.type());
		}
	}

	/**
	 * Returns the index of this attribute.
	 *
	 * @return the index of this attribute
	 */
	//@ ensures \result == m_Index;
	public final /*@ pure @*/ int index() {

		return m_Index;
	}

	/**
	 * Returns the index of a given attribute value. (The index of
	 * the first occurence of this value.)
	 *
	 * @param value the value for which the index is to be returned
	 * @return the index of the given attribute value if attribute
	 * is nominal or a string, -1 if it is numeric or the value 
	 * can't be found
	 */
	public final int indexOfValue(String value) {

		if (!isNominal() && !isString())
			return -1;
		Object store = value;
		if (value.length() > STRING_COMPRESS_THRESHOLD) {
			try {
				store = new SerializedObject(value, true);
			} catch (Exception ex) {
				System.err.println("Couldn't compress string attribute value -"
						+ " searching uncompressed.");
			}
		}
		Integer val = (Integer)m_Hashtable.get(store);
		if (val == null) return -1;
		else return val.intValue();
	}

	/**
	 * Test if the attribute is nominal.
	 *
	 * @return true if the attribute is nominal
	 */
	//@ ensures \result <==> (m_Type == NOMINAL);
	public final /*@ pure @*/ boolean isNominal() {

		return (m_Type == NOMINAL);
	}

	/**
	 * Tests if the attribute is numeric.
	 *
	 * @return true if the attribute is numeric
	 */
	//@ ensures \result <==> ((m_Type == NUMERIC) || (m_Type == DATE));
	public final /*@ pure @*/ boolean isNumeric() {

		return ((m_Type == NUMERIC) || (m_Type == DATE));
	}

	/**
	 * Tests if the attribute is a string.
	 *
	 * @return true if the attribute is a string
	 */
	//@ ensures \result <==> (m_Type == STRING);
	public final /*@ pure @*/ boolean isString() {

		return (m_Type == STRING);
	}

	/**
	 * Tests if the attribute is a date type.
	 *
	 * @return true if the attribute is a date type
	 */
	//@ ensures \result <==> (m_Type == DATE);
	public final /*@ pure @*/ boolean isDate() {

		return (m_Type == DATE);
	}

	/**
	 * Returns the attribute's name.
	 *
	 * @return the attribute's name as a string
	 */
	//@ ensures \result == m_Name;
	public final /*@ pure @*/ String name() {

		return m_Name;
	}

	/**
	 * Returns the number of attribute values. Returns 0 for numeric attributes.
	 *
	 * @return the number of attribute values
	 */
	public final /*@ pure @*/ int numValues() {

		if (!isNominal() && !isString()) {
			return 0;
		} else {
			return m_Values.size();
		}
	}

	/**
	 * Returns a description of this attribute in ARFF format. Quotes
	 * strings if they contain whitespace characters, or if they
	 * are a question mark.
	 *
	 * @return a description of this attribute as a string
	 */
	public final String toString() {

		StringBuffer text = new StringBuffer();

		text.append(ARFF_ATTRIBUTE).append(" ").append(Utils.quote(m_Name)).append(" ");
		switch (m_Type) {
		case NOMINAL:
			text.append('{');
			Enumeration enu = enumerateValues();
			while (enu.hasMoreElements()) {
				text.append(Utils.quote((String) enu.nextElement()));
				if (enu.hasMoreElements())
					text.append(',');
			}
			text.append('}');
			break;
		case NUMERIC:
			text.append(ARFF_ATTRIBUTE_NUMERIC);
			break;
		case STRING:
			text.append(ARFF_ATTRIBUTE_STRING);
			break;
		case DATE:
			text.append(ARFF_ATTRIBUTE_DATE).append(" ").append(Utils.quote(m_DateFormat.toPattern()));
			break;
		default:
			text.append("UNKNOWN");
		break;
		}
		return text.toString();
	}

	/**
	 * Returns the attribute's type as an integer.
	 *
	 * @return the attribute's type.
	 */
	//@ ensures \result == m_Type;
	public final /*@ pure @*/ int type() {

		return m_Type;
	}

	/**
	 * Returns a value of a nominal or string attribute. 
	 * Returns an empty string if the attribute is neither
	 * nominal nor a string attribute.
	 *
	 * @param valIndex the value's index
	 * @return the attribute's value as a string
	 */
	public final /*@ non_null pure @*/ String value(int valIndex) {

		if (!isNominal() && !isString()) {
			return "";
		} else {
			Object val = m_Values.elementAt(valIndex);

			// If we're storing strings compressed, uncompress it.
			if (val instanceof SerializedObject) {
				val = ((SerializedObject)val).getObject();
			}
			return (String) val;
		}
	}

	/**
	 * Constructor for a numeric attribute with a particular index.
	 *
	 * @param attributeName the name for the attribute
	 * @param index the attribute's index
	 */
	//@ requires attributeName != null;
	//@ requires index >= 0;
	//@ ensures  m_Name == attributeName;
	//@ ensures  m_Index == index;
	Attribute(String attributeName, int index) {

		this(attributeName);
		m_Index = index;
	}

	/**
	 * Constructor for date attributes with a particular index.
	 *
	 * @param attributeName the name for the attribute
	 * @param dateFormat a string suitable for use with
	 * SimpleDateFormatter for parsing dates.  Null for a default format
	 * string.
	 * @param index the attribute's index
	 */
	//@ requires attributeName != null;
	//@ requires index >= 0;
	//@ ensures  m_Name == attributeName;
	//@ ensures  m_Index == index;
	Attribute(String attributeName, String dateFormat, 
			int index) {

		this(attributeName, dateFormat);
		m_Index = index;
	}

	/**
	 * Constructor for nominal attributes and string attributes with
	 * a particular index.
	 * If a null vector of attribute values is passed to the method,
	 * the attribute is assumed to be a string.
	 *
	 * @param attributeName the name for the attribute
	 * @param attributeValues a vector of strings denoting the attribute values.
	 * Null if the attribute is a string attribute.
	 * @param index the attribute's index
	 */
	//@ requires attributeName != null;
	//@ requires index >= 0;
	//@ ensures  m_Name == attributeName;
	//@ ensures  m_Index == index;
	Attribute(String attributeName, FastVector attributeValues, 
			int index) {

		this(attributeName, attributeValues);
		m_Index = index;
	}

	/**
	 * Adds a string value to the list of valid strings for attributes
	 * of type STRING and returns the index of the string.
	 *
	 * @param value The string value to add
	 * @return the index assigned to the string, or -1 if the attribute is not
	 * of type Attribute.STRING 
	 */
	/*@ requires value != null;
      ensures  isString() && 0 <= \result && \result < m_Values.size() ||
             ! isString() && \result == -1;
	 */
	public int addStringValue(String value) {

		if (!isString()) {
			return -1;
		}
		Object store = value;

		if (value.length() > STRING_COMPRESS_THRESHOLD) {
			try {
				store = new SerializedObject(value, true);
			} catch (Exception ex) {
				System.err.println("Couldn't compress string attribute value -"
						+ " storing uncompressed.");
			}
		}
		Integer index = (Integer)m_Hashtable.get(store);
		if (index != null) {
			return index.intValue();
		} else {
			int intIndex = m_Values.size();
			m_Values.addElement(store);
			m_Hashtable.put(store, new Integer(intIndex));
			return intIndex;
		}
	}

	/**
	 * Adds a string value to the list of valid strings for attributes
	 * of type STRING and returns the index of the string. This method is
	 * more efficient than addStringValue(String) for long strings.
	 *
	 * @param src The Attribute containing the string value to add.
	 * @param int index the index of the string value in the source attribute.
	 * @return the index assigned to the string, or -1 if the attribute is not
	 * of type Attribute.STRING 
	 */
	/*@ requires src != null;
      requires 0 <= index && index < src.m_Values.size();
      ensures  isString() && 0 <= \result && \result < m_Values.size() ||
             ! isString() && \result == -1;
	 */
	public int addStringValue(Attribute src, int index) {

		if (!isString()) {
			return -1;
		}
		Object store = src.m_Values.elementAt(index);
		Integer oldIndex = (Integer)m_Hashtable.get(store);
		if (oldIndex != null) {
			return oldIndex.intValue();
		} else {
			int intIndex = m_Values.size();
			m_Values.addElement(store);
			m_Hashtable.put(store, new Integer(intIndex));
			return intIndex;
		}
	}

	/**
	 * Adds an attribute value. Creates a fresh list of attribute
	 * values before adding it.
	 *
	 * @param value the attribute value
	 */
	final void addValue(String value) {

		m_Values = (FastVector)m_Values.copy();
		m_Hashtable = (Hashtable)m_Hashtable.clone();
		forceAddValue(value);
	}

	/**
	 * Produces a shallow copy of this attribute with a new name.
	 *
	 * @param newName the name of the new attribute
	 * @return a copy of this attribute with the same index
	 */
	//@ requires newName != null;
	//@ ensures \result.m_Name  == newName;
	//@ ensures \result.m_Index == m_Index;
	//@ ensures \result.m_Type  == m_Type;
	final /*@ pure non_null @*/ Attribute copy(String newName) {

		Attribute copy = new Attribute(newName);

		copy.m_Index = m_Index;
		copy.m_DateFormat = m_DateFormat;
		copy.m_Type = m_Type;
		copy.m_Values = m_Values;
		copy.m_Hashtable = m_Hashtable;
		copy.setMetadata(m_Metadata);

		return copy;
	}

	/**
	 * Removes a value of a nominal or string attribute. Creates a 
	 * fresh list of attribute values before removing it.
	 *
	 * @param index the value's index
	 * @exception IllegalArgumentException if the attribute is not nominal
	 */
	//@ requires isNominal() || isString();
	//@ requires 0 <= index && index < m_Values.size();
	final void delete(int index) {

		if (!isNominal() && !isString()) 
			throw new IllegalArgumentException("Can only remove value of" +
			"nominal or string attribute!");
		else {
			m_Values = (FastVector)m_Values.copy();
			m_Values.removeElementAt(index);
			Hashtable hash = new Hashtable(m_Hashtable.size());
			Enumeration enu = m_Hashtable.keys();
			while (enu.hasMoreElements()) {
				Object string = enu.nextElement();
				Integer valIndexObject = (Integer)m_Hashtable.get(string);
				int valIndex = valIndexObject.intValue();
				if (valIndex > index) {
					hash.put(string, new Integer(valIndex - 1));
				} else if (valIndex < index) {
					hash.put(string, valIndexObject);
				}
			}
			m_Hashtable = hash;
		}
	}

	/**
	 * Adds an attribute value.
	 *
	 * @param value the attribute value
	 */
	//@ requires value != null;
	//@ ensures  m_Values.size() == \old(m_Values.size()) + 1;
	final void forceAddValue(String value) {

		Object store = value;
		if (value.length() > STRING_COMPRESS_THRESHOLD) {
			try {
				store = new SerializedObject(value, true);
			} catch (Exception ex) {
				System.err.println("Couldn't compress string attribute value -"
						+ " storing uncompressed.");
			}
		}
		m_Values.addElement(store);
		m_Hashtable.put(store, new Integer(m_Values.size() - 1));
	}

	/**
	 * Sets the index of this attribute.
	 *
	 * @param the index of this attribute
	 */
	//@ requires 0 <= index;
	//@ assignable m_Index;
	//@ ensures m_Index == index;
	final void setIndex(int index) {

		m_Index = index;
	}

	/**
	 * Sets a value of a nominal attribute or string attribute.
	 * Creates a fresh list of attribute values before it is set.
	 *
	 * @param index the value's index
	 * @param string the value
	 * @exception IllegalArgumentException if the attribute is not nominal or 
	 * string.
	 */
	//@ requires string != null;
	//@ requires isNominal() || isString();
	//@ requires 0 <= index && index < m_Values.size();
	final void setValue(int index, String string) {

		switch (m_Type) {
		case NOMINAL:
		case STRING:
			m_Values = (FastVector)m_Values.copy();
			m_Hashtable = (Hashtable)m_Hashtable.clone();
			Object store = string;
			if (string.length() > STRING_COMPRESS_THRESHOLD) {
				try {
					store = new SerializedObject(string, true);
				} catch (Exception ex) {
					System.err.println("Couldn't compress string attribute value -"
							+ " storing uncompressed.");
				}
			}
			m_Hashtable.remove(m_Values.elementAt(index));
			m_Values.setElementAt(store, index);
			m_Hashtable.put(store, new Integer(index));
			break;
		default:
			throw new IllegalArgumentException("Can only set values for nominal"
					+ " or string attributes!");
		}
	}

	//@ requires isDate();
	public /*@pure@*/ String formatDate(double date) {
		switch (m_Type) {
		case DATE:
			return m_DateFormat.format(new Date((long)date));
		default:
			throw new IllegalArgumentException("Can only format date values for date"
					+ " attributes!");
		}
	}

	//@ requires isDate();
	//@ requires string != null;
	public double parseDate(String string) throws ParseException {
		switch (m_Type) {
		case DATE:
			long time = m_DateFormat.parse(string).getTime();
			// TODO put in a safety check here if we can't store the value in a double.
			return (double)time;
		default:
			throw new IllegalArgumentException("Can only parse date values for date"
					+ " attributes!");
		}
	}

	/**
	 * Returns the properties supplied for this attribute.
	 *
	 * @return metadata for this attribute
	 */  
	public final /*@ pure @*/ ProtectedProperties getMetadata() {

		return m_Metadata;
	}

	/**
	 * Returns the ordering of the attribute. One of the following:
	 * 
	 * ORDERING_SYMBOLIC - attribute values should be treated as symbols.
	 * ORDERING_ORDERED  - attribute values have a global ordering.
	 * ORDERING_MODULO   - attribute values have an ordering which wraps.
	 *
	 * @return the ordering type of the attribute
	 */
	public final /*@ pure @*/ int ordering() {

		return m_Ordering;
	}

	/**
	 * Returns whether the attribute values are equally spaced.
	 *
	 * @return whether the attribute is regular or not
	 */
	public final /*@ pure @*/ boolean isRegular() {

		return m_IsRegular;
	}

	/**
	 * Returns whether the attribute can be averaged meaningfully.
	 *
	 * @return whether the attribute can be averaged or not
	 */
	public final /*@ pure @*/ boolean isAveragable() {

		return m_IsAveragable;
	}

	/**
	 * Returns whether the attribute has a zeropoint and may be
	 * added meaningfully.
	 *
	 * @return whether the attribute has a zeropoint or not
	 */
	public final /*@ pure @*/ boolean hasZeropoint() {

		return m_HasZeropoint;
	}

	/**
	 * Returns the attribute's weight.
	 *
	 * @return the attribute's weight as a double
	 */
	public final /*@ pure @*/ double weight() {

		return m_Weight;
	}

	/**
	 * Returns the lower bound of a numeric attribute.
	 *
	 * @return the lower bound of the specified numeric range
	 */
	public final /*@ pure @*/ double getLowerNumericBound() {

		return m_LowerBound;
	}

	/**
	 * Returns whether the lower numeric bound of the attribute is open.
	 *
	 * @return whether the lower numeric bound is open or not (closed)
	 */
	public final /*@ pure @*/ boolean lowerNumericBoundIsOpen() {

		return m_LowerBoundIsOpen;
	}

	/**
	 * Returns the upper bound of a numeric attribute.
	 *
	 * @return the upper bound of the specified numeric range
	 */
	public final /*@ pure @*/ double getUpperNumericBound() {

		return m_UpperBound;
	}

	/**
	 * Returns whether the upper numeric bound of the attribute is open.
	 *
	 * @return whether the upper numeric bound is open or not (closed)
	 */
	public final /*@ pure @*/ boolean upperNumericBoundIsOpen() {

		return m_UpperBoundIsOpen;
	}

	/**
	 * Determines whether a value lies within the bounds of the attribute.
	 *
	 * @return whether the value is in range
	 */
	public final /*@ pure @*/ boolean isInRange(double value) {

		// dates and missing values are a special case 
		if (m_Type == DATE || value == Instance.missingValue()) return true;
		if (m_Type != NUMERIC) {
			// do label range check
			int intVal = (int) value;
			if (intVal < 0 || intVal >= m_Hashtable.size()) return false;
		} else {
			// do numeric bounds check
			if (m_LowerBoundIsOpen) {
				if (value <= m_LowerBound) return false;
			} else {
				if (value < m_LowerBound) return false;
			}
			if (m_UpperBoundIsOpen) {
				if (value >= m_UpperBound) return false;
			} else {
				if (value > m_UpperBound) return false;
			}
		}
		return true;
	}

	/**
	 * Sets the metadata for the attribute. Processes the strings stored in the
	 * metadata of the attribute so that the properties can be set up for the
	 * easy-access metadata methods. Any strings sought that are omitted will
	 * cause default values to be set.
	 * 
	 * The following properties are recognised:
	 * ordering, averageable, zeropoint, regular, weight, and range.
	 *
	 * All other properties can be queried and handled appropriately by classes
	 * calling the getMetadata() method.
	 *
	 * @param metadata the metadata
	 * @exception IllegalArgumentException if the properties are not consistent
	 */
	//@ requires metadata != null;
	private void setMetadata(ProtectedProperties metadata) {

		m_Metadata = metadata;

		if (m_Type == DATE) {
			m_Ordering = ORDERING_ORDERED;
			m_IsRegular = true;
			m_IsAveragable = false;
			m_HasZeropoint = false;
		} else {

			// get ordering
			String orderString = m_Metadata.getProperty("ordering","");

			// numeric ordered attributes are averagable and zeropoint by default
			String def;
			if (m_Type == NUMERIC
					&& orderString.compareTo("modulo") != 0
					&& orderString.compareTo("symbolic") != 0)
				def = "true";
			else def = "false";

			// determine boolean states
			m_IsAveragable =
				(m_Metadata.getProperty("averageable",def).compareTo("true") == 0);
			m_HasZeropoint =
				(m_Metadata.getProperty("zeropoint",def).compareTo("true") == 0);
			// averagable or zeropoint implies regular
			if (m_IsAveragable || m_HasZeropoint) def = "true";
			m_IsRegular =
				(m_Metadata.getProperty("regular",def).compareTo("true") == 0);

			// determine ordering
			if (orderString.compareTo("symbolic") == 0)
				m_Ordering = ORDERING_SYMBOLIC;
			else if (orderString.compareTo("ordered") == 0)
				m_Ordering = ORDERING_ORDERED;
			else if (orderString.compareTo("modulo") == 0)
				m_Ordering = ORDERING_MODULO;
			else {
				if (m_Type == NUMERIC || m_IsAveragable || m_HasZeropoint)
					m_Ordering = ORDERING_ORDERED;
				else m_Ordering = ORDERING_SYMBOLIC;
			}
		}

		// consistency checks
		if (m_IsAveragable && !m_IsRegular)
			throw new IllegalArgumentException("An averagable attribute must be"
					+ " regular");
		if (m_HasZeropoint && !m_IsRegular)
			throw new IllegalArgumentException("A zeropoint attribute must be"
					+ " regular");
		if (m_IsRegular && m_Ordering == ORDERING_SYMBOLIC)
			throw new IllegalArgumentException("A symbolic attribute cannot be"
					+ " regular");
		if (m_IsAveragable && m_Ordering != ORDERING_ORDERED)
			throw new IllegalArgumentException("An averagable attribute must be"
					+ " ordered");
		if (m_HasZeropoint && m_Ordering != ORDERING_ORDERED)
			throw new IllegalArgumentException("A zeropoint attribute must be"
					+ " ordered");

		// determine weight
		m_Weight = 1.0;
		String weightString = m_Metadata.getProperty("weight");
		if (weightString != null) {
			try{
				m_Weight = Double.valueOf(weightString).doubleValue();
			} catch (NumberFormatException e) {
				// Check if value is really a number
				throw new IllegalArgumentException("Not a valid attribute weight: '" 
						+ weightString + "'");
			}
		}

		// determine numeric range
		if (m_Type == NUMERIC) setNumericRange(m_Metadata.getProperty("range"));
	}

	/**
	 * Sets the numeric range based on a string. If the string is null the range
	 * will default to [-inf,+inf]. A square brace represents a closed interval, a
	 * curved brace represents an open interval, and 'inf' represents infinity.
	 * Examples of valid range strings: "[-inf,20)","(-13.5,-5.2)","(5,inf]"
	 *
	 * @param rangeString the string to parse as the attribute's numeric range
	 * @exception IllegalArgumentException if the range is not valid
	 */
	//@ requires rangeString != null;
	private void setNumericRange(String rangeString)
	{
		// set defaults
		m_LowerBound = Double.NEGATIVE_INFINITY;
		m_LowerBoundIsOpen = false;
		m_UpperBound = Double.POSITIVE_INFINITY;
		m_UpperBoundIsOpen = false;

		if (rangeString == null) return;

		// set up a tokenzier to parse the string
		StreamTokenizer tokenizer =
			new StreamTokenizer(new StringReader(rangeString));
		tokenizer.resetSyntax();         
		tokenizer.whitespaceChars(0, ' ');    
		tokenizer.wordChars(' '+1,'\u00FF');
		tokenizer.ordinaryChar('[');
		tokenizer.ordinaryChar('(');
		tokenizer.ordinaryChar(',');
		tokenizer.ordinaryChar(']');
		tokenizer.ordinaryChar(')');

		try {

			// get opening brace
			tokenizer.nextToken();

			if (tokenizer.ttype == '[') m_LowerBoundIsOpen = false;
			else if (tokenizer.ttype == '(') m_LowerBoundIsOpen = true;
			else throw new IllegalArgumentException("Expected opening brace on range,"
					+ " found: "
					+ tokenizer.toString());

			// get lower bound
			tokenizer.nextToken();
			if (tokenizer.ttype != tokenizer.TT_WORD)
				throw new IllegalArgumentException("Expected lower bound in range,"
						+ " found: "
						+ tokenizer.toString());
			if (tokenizer.sval.compareToIgnoreCase("-inf") == 0)
				m_LowerBound = Double.NEGATIVE_INFINITY;
			else if (tokenizer.sval.compareToIgnoreCase("+inf") == 0)
				m_LowerBound = Double.POSITIVE_INFINITY;
			else if (tokenizer.sval.compareToIgnoreCase("inf") == 0)
				m_LowerBound = Double.NEGATIVE_INFINITY;
			else try {
				m_LowerBound = Double.valueOf(tokenizer.sval).doubleValue();
			} catch (NumberFormatException e) {
				throw new IllegalArgumentException("Expected lower bound in range,"
						+ " found: '" + tokenizer.sval + "'");
			}

			// get separating comma
			if (tokenizer.nextToken() != ',')
				throw new IllegalArgumentException("Expected comma in range,"
						+ " found: "
						+ tokenizer.toString());

			// get upper bound
			tokenizer.nextToken();
			if (tokenizer.ttype != tokenizer.TT_WORD)
				throw new IllegalArgumentException("Expected upper bound in range,"
						+ " found: "
						+ tokenizer.toString());
			if (tokenizer.sval.compareToIgnoreCase("-inf") == 0)
				m_UpperBound = Double.NEGATIVE_INFINITY;
			else if (tokenizer.sval.compareToIgnoreCase("+inf") == 0)
				m_UpperBound = Double.POSITIVE_INFINITY;
			else if (tokenizer.sval.compareToIgnoreCase("inf") == 0)
				m_UpperBound = Double.POSITIVE_INFINITY;
			else try {
				m_UpperBound = Double.valueOf(tokenizer.sval).doubleValue();
			} catch (NumberFormatException e) {
				throw new IllegalArgumentException("Expected upper bound in range,"
						+ " found: '" + tokenizer.sval + "'");
			}

			// get closing brace
			tokenizer.nextToken();

			if (tokenizer.ttype == ']') m_UpperBoundIsOpen = false;
			else if (tokenizer.ttype == ')') m_UpperBoundIsOpen = true;
			else throw new IllegalArgumentException("Expected closing brace on range,"
					+ " found: "
					+ tokenizer.toString());

			// check for rubbish on end
			if (tokenizer.nextToken() != tokenizer.TT_EOF)
				throw new IllegalArgumentException("Expected end of range string,"
						+ " found: "
						+ tokenizer.toString());

		} catch (IOException e) {
			throw new IllegalArgumentException("IOException reading attribute range"
					+ " string: " + e.getMessage());
		}

		if (m_UpperBound < m_LowerBound)
			throw new IllegalArgumentException("Upper bound (" + m_UpperBound
					+ ") on numeric range is"
					+ " less than lower bound ("
					+ m_LowerBound + ")!");
	}

	/**
	 * Simple main method for testing this class.
	 */
	//@ requires ops != null;
	//@ requires \nonnullelements(ops);
	public static void main(String[] ops) {

		try {

			// Create numeric attributes "length" and "weight"
			Attribute length = new Attribute("length");
			Attribute weight = new Attribute("weight");

			// Create date attribute "date"
			Attribute date = new Attribute("date", "yyyy-MM-dd HH:mm:ss");

			System.out.println(date);
			double dd = date.parseDate("2001-04-04 14:13:55");
			System.out.println("Test date = " + dd);
			System.out.println(date.formatDate(dd));

			dd = new Date().getTime();
			System.out.println("Date now = " + dd);
			System.out.println(date.formatDate(dd));

			// Create vector to hold nominal values "first", "second", "third" 
			FastVector my_nominal_values = new FastVector(3); 
			my_nominal_values.addElement("first"); 
			my_nominal_values.addElement("second"); 
			my_nominal_values.addElement("third"); 

			// Create nominal attribute "position" 
			Attribute position = new Attribute("position", my_nominal_values);

			// Print the name of "position"
			System.out.println("Name of \"position\": " + position.name());

			// Print the values of "position"
			Enumeration attValues = position.enumerateValues();
			while (attValues.hasMoreElements()) {
				String string = (String)attValues.nextElement();
				System.out.println("Value of \"position\": " + string);
			}

			// Shallow copy attribute "position"
			Attribute copy = (Attribute) position.copy();

			// Test if attributes are the same
			System.out.println("Copy is the same as original: " + copy.equals(position));

			// Print index of attribute "weight" (should be unset: -1)
			System.out.println("Index of attribute \"weight\" (should be -1): " + 
					weight.index());

			// Print index of value "first" of attribute "position"
			System.out.println("Index of value \"first\" of \"position\" (should be 0): " +
					position.indexOfValue("first"));

			// Tests type of attribute "position"
			System.out.println("\"position\" is numeric: " + position.isNumeric());
			System.out.println("\"position\" is nominal: " + position.isNominal());
			System.out.println("\"position\" is string: " + position.isString());

			// Prints name of attribute "position"
			System.out.println("Name of \"position\": " + position.name());

			// Prints number of values of attribute "position"
			System.out.println("Number of values for \"position\": " + position.numValues());

			// Prints the values (againg)
			for (int i = 0; i < position.numValues(); i++) {
				System.out.println("Value " + i + ": " + position.value(i));
			}

			// Prints the attribute "position" in ARFF format
			System.out.println(position);

			// Checks type of attribute "position" using constants
			switch (position.type()) {
			case Attribute.NUMERIC:
				System.out.println("\"position\" is numeric");
				break;
			case Attribute.NOMINAL:
				System.out.println("\"position\" is nominal");
				break;
			case Attribute.STRING:
				System.out.println("\"position\" is string");
				break;
			case Attribute.DATE:
				System.out.println("\"position\" is date");
				break;
			default:
				System.out.println("\"position\" has unknown type");
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

